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STEEL BOLTS or PLASTIC

Old 11-27-2005, 08:52 PM
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marwen1
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Default STEEL BOLTS or PLASTIC

When I use bolts to hold down my removeable wing(s), which is beet to use? Plastic (nylon) or steel?

Is there a reason why I see the plastic ones moreso than the sttel?


marwen
Old 11-27-2005, 10:05 PM
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N1EDM
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Default RE: STEEL BOLTS or PLASTIC

I'd go for the nylon ones. I've never had a problem with wings coming loose with the nylon, and it might save you a bit of grief after a crash. It might minimize damage.

Also, I might also recommend that you use them for landing gear as well. They've saved my rear end many times. Come in for a rough landing after a deadstick, and the lg comes off, but the wood in the fuselage stays put.

Also, you might notice that if you use a size #10 screw, look for a 10-24 thread, not a 10-32. They thread in much easier. I usually go into T-nuts instead of tapping the wood directly.

Just my $.02

Bob
Old 11-28-2005, 09:42 AM
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da Rock
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Default RE: STEEL BOLTS or PLASTIC

N1EDM is right on.

I've just started flying a Phoenix .46 Sukhoi. It was designed with steel bolts to hold the gear on. I swapped those t-nuts out for ones that fit the nylon bolts I happened to have in the shop. The 2nd landing of the a/c was 1' too far left and the a/c was tripped up by the soybean stubble. The a/c hooked a gear strut and flipped. Nothing broke on the a/c and the gear stayed put. Good deal, as that proved the bolts were big enough to stand light stress. A couple of days later during the a/c's 2nd day of trim-out, I landed hot and long and braindead on what was going to be a touch and go and at the last minute was going to be a landing. I should have gone around. Went off into the soybean stubble way too fast and tore the gear off. Nothing else looked other than brand new other than having some soybean chaff stuck here and there. Good deal, as that proved the bolts were small enough to give under heavy stress.

I retrofit every a/c's gear bolts with nylon. It takes less time to do it than to type out the description of how to do it. Knock out the original t-nuts by threading the iron bolts in half-way and then tapping on them with something that's moderately heavy. Look first to make sure the t-nuts aren't glued in. I've never seen any that were. Then run a drill bit into the holes so they match then new t-nuts. The new ones will be wider. Stick the new ones into the holes and tighten them in.

Wing bolts too.

And there are some very small nylon bolts available too. They do a good job holding fiberglass cowls on instead of those steel wood screws. Yeah, they're usually a bit larger, but you can stain their heads to match the cowl color. They aren't usually worth the effort except on larger models because there isn't usually enough room for their t-nuts on smaller a/c.
Old 11-28-2005, 12:15 PM
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Default RE: STEEL BOLTS or PLASTIC

You want the bolts that hold the wing and landing gear to be weaker than the surrounding structure. When you come in for a hard landing and if the bolts that hold the landing gear on are stronger than the surrounding structure you can guess what is going to give first. By using the plastic bolts they will fail first reducing the damage to the fuselage and surrounding structure. You would be surprised how much load the plastic bolts can take.

Good luck..

I just rebuilt my fuselage on my Piper Cub because I had very strong bolts holding the gear on. If I had plastic bolts, I could have recovered the bottom of the fuselage, and flown that same day, but instead I had to re-build the entire bottom section of the plane.
Old 11-28-2005, 01:03 PM
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Default RE: STEEL BOLTS or PLASTIC

For some reason, most everyone is talking about bolts for LANDING GEAR.

All well and good. I am sure that the reasons given will also apply for a glider wing.

As that is what my overall intended use is for.

marwen
Old 11-28-2005, 01:04 PM
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Default RE: STEEL BOLTS or PLASTIC

Darock,

What size nylon bolts did you just happen to have lying around the shop?
How heavy is the plane you put them in?
How many bolts did you use?

Greg
Old 11-28-2005, 08:02 PM
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N1EDM
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Default RE: STEEL BOLTS or PLASTIC

Marwen, I was referring to bolts for both the gear and the wing. I only mentioned the gear to give a feel for how they would perform.

I have a Sig Rascal 40 (about 6' span) and it's held on with two 10-24 nylon bolts. Never had a problem with them. I do replace them once every season, just to make sure they didn't stretch on me.

I prefer the coarser thread of the 10-24 instead of the fine thread 10-32, at least for the nylon ones. Easier to thread.

Bob
Old 11-28-2005, 10:17 PM
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Default RE: STEEL BOLTS or PLASTIC

That wing of mine (The AIRHOPPER - 1940 vintage) has a shallow "V" shape for its center section. I figure That I'll leave the center section permanently in place and simply take off the 36" wing extention sections after each trip to the field. In case I have to make adjustments to the servos, I'll have to be able to get to them -- seeing as how they are located immediately underneath.

That hardware I use is simply called an "insert". I drill a 3/8" hole, take a 1/4" allen wrench and twist it into the hardwood. I only had ONE of them when I started this project, so I spent an hour or so this PM at HOME DEPOT. Man, I found all kinds of great little stuff.

Hah! $20 later --- LOL

The 10-24 inserts had a recessed slot instead of an allen opening. After I intalled the pair of them, I feel that the hardwood really compressed the top end. The NYLON bolds would not even start to thread in. They would go in from the bottom, so I knew that I got thr correct threads so as much as I didn't want to use steel, I had to. It is the only material that would start making the hold down


marwen
Old 11-28-2005, 11:04 PM
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SoCal GliderGuider
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Default RE: STEEL BOLTS or PLASTIC

Your wing is pretty much locked into the fuse structure. Large nylon taped into ply or smaller steel with blind nuts will do the job. Have to add reinforcements inside the wing for these to go through as well as the plywood keyed into the fuse structure to secure to.
Old 11-29-2005, 10:01 AM
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the-plumber
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Default RE: STEEL BOLTS or PLASTIC


ORIGINAL: marwen

When I use bolts to hold down my removeable wing(s), which is beet to use? Plastic (nylon) or steel?

Is there a reason why I see the plastic ones moreso than the sttel?
Use nylon 6/6 machine screws (bolts) preferrably with a "cheese" or "pan" head.

They are commonly used becuase they will shear on hard impact, preserving the underlying structure.

I find it most expedient to use drilled and tapped hardwood mounting blocks in the airframe, for wings or landing gear.

Been doing that since my second model, right after I got tired of snapping rubber bands. Never had a failure except as desired - several models were subjected to less than wonderful landings, and the only repair needed was fishing out the broken off nylon bolts and recovering the bottoms of a few fuselages.

My Dad put "our" trainer into a screaming power dive and yanked full up elevator - the wings assumed the prayer position, but the nylon bolts were still holding the center section on the fuse when we finally found the debris pile.
Old 11-29-2005, 10:35 AM
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Default RE: STEEL BOLTS or PLASTIC

Hi Fred

I think then I should go out to thye tool stoe and buy a set of EASY OUTS -- LOL

marwen

By golly, I look at my last post -- I can't spell either.

Ha! Ha!
Old 11-29-2005, 10:59 AM
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Default RE: STEEL BOLTS or PLASTIC

Instead of tapping the hardwood, I drill a 3/8 hole and screw an aluminum insert into it.

VOILA!

marwen
Old 11-29-2005, 06:34 PM
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da Rock
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Default RE: STEEL BOLTS or PLASTIC

Marwen,
the inserts sound like a great idea. And seems like brass ones are sold at the LHS.

OldRookie,
I put them in everything I build, and every ARF I stick together. The a/c mentioned in the post, a Phoenix .46 Sukhoi, has your everyday sheet aluminum gear only it's two piece. It's exactly like one piece, only split in the middle, so there is a left and right. Since they did that, each side has to have two bolt holes. It's not the most sensible design for an a/c model since a one piece gear would have only needed 3 holes to have left-to-right and front-to-back strength. As it is, they stuck in 4 holes in a line, so the bolt positions don't have any extra mechanical advantage for front to back, but I'm digressing.... The model box says the a/c flying weight will be 5.7 - 6.2 pounds which seems a bit heavy for a .46 (but isn't a problem at all for my OS.46AX) and I did a few things that brought mine out at the low figure. Mine is 5lb10oz.

Since each gear side only goes half-way across the fuselage, each gear side is going to fulcrum near where the outside bolt is. The inside bolt is going to have to deal with all the stress of every landing. (Single piece gear wouldn't have any of this problem.) And the outside bolt is going to be along for the ride most of the time. So I put 10-24 nylons through the inside holes. And I had some 8-32 nylons I used for the outside holes. and.......

Turns out that the ARF designers have the gear "imbedded" into the fuselage yet didn't bother to fill in the missing fuselage area that'd be where the gear is. The front of the fuselage comes back to the gear and stops at a big hole. And the fuselage/wing picks up after the big hole. So you got a round underside front to back with this "slot" where the gear is. So....

I took a few minutes while sticking the thing together and whipped a plug out to strengthen the gear attachment that would also fill the hole. I made it starting with a piece of plywood that had some pink foam glued to it. I shaped to foam to match the fuselage bottom the thinned it to take 1/16 balsa sheet (for strength) on it's outside face. It reaches from the bend in the left side gear piece to the bend in the right side gear piece. It's obviously drilled so the 4 gear bolts can reach through. But the bolts now actually tighten down onto the plywood. So I got a piece of plywood that is tightened down on the gear halves. It should help greatly to resist the landing stress on the gear that's going to try and lever out the gear every landing. It distributes the leverage to the plywood and 4 bolts instead of the original one bolt on each side.

So I got a couple of 8-32s on the outside two holes and a couple of 10-24s on the inside two holes and a plywood plate distributing any load to all 4 bolts. And thanks to my flying mistakes, I've tested the system with exactly the "right" tests and it's passed perfectly. I've proved that it's weak enough and that it's strong enough. Time will tell how durable it is, and that's easily helped out by my habit of putting new nylon bolts in the start of every new flying season.

I think I posted a picture of that filler block somewhere on these forums.....
Old 11-29-2005, 09:19 PM
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marwen1
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Default RE: STEEL BOLTS or PLASTIC


[quote]ORIGINAL: darock

Marwen,
the inserts sound like a great idea. And seems like brass ones are sold at the LHS.



Yep! Sure are. Now go to RONA or else HOME DEPOT

half the price

same thing with the NYLON BOLTS


marwen
Old 11-30-2005, 09:36 PM
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Default RE: STEEL BOLTS or PLASTIC


ORIGINAL: marwen
I think then I should go out to thye tool stoe and buy a set of EASY OUTS -- LOL
Not necessary.

When the nylon bolts shear off, the remnants in the threaded mounting blocks are not under any tension - they're just sitting there waiting to be unscrewed, and the 'difficult' part is getting hold of the stumps. Sometimes I can fiddle them out with a fingernail, sometimes I 'bump the stump' with a Dremel cutoff wheel to form a screwdriver slot, and simply unscrew the things. Never had to use easyouts or anything of the sort to remove nylon bolt stumps.
Old 11-30-2005, 10:21 PM
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Default RE: STEEL BOLTS or PLASTIC

Right now, I have two different sets and two different sizes of NYLON bolts.. 1/4 - 20 & 10-24.

Solid maple hardwood blocks have 3/8" hole drilled oput to accect the inserts for both sizes. The larger set is working 100%, with the smaller of the two, when I try to screw in the NYLON bolts, they won't even start. However, a steel one goes in like butter.

The LARGER set was intalled with an ALLEN head. The smaller only had a straight CUT. So, I had to install the insets with a SLOT screw driver. I think what is happening here is that the maple hardwood is cpmopressing the open slot area. The soft NYLON just wount hold up to the pressure. When I isolate the problem and start the small NYLON from the exit side, it goes right in without any problem

I thinkl what I'll do, is try to find a differnt source for my inset screw and try to fimd asn ALLEN for the smaller size as well. Otherwise, I will be copelled to use the steel. It's onlt a 1.5" bolt and it is at the trailing edge of the wing for the sailplane.

It MUST go down RIGHT simply because once it is all said and done, the top cover for the wing and the screws will have a permanent TURTLE DECK.

A lot of work to have it all screw up.

hah! No pun intended.


marwen
Old 11-30-2005, 10:33 PM
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Default RE: STEEL BOLTS or PLASTIC

Hi guys
I have an interesting point for this thread. Nylon bolts are great for our hobby, I always use them as you all are describing. Not everyone seems to know that Nylon seems to have a small percentage of water in it, so if you fly in the winter, it pays to know how easy Nylon bolts can break. If you have a spare one that is maybe buggered up a bit, for an experiment, put it in the freezer for a while. You will be surprise how easy it will break when frozen. I used a couple of Nylon bolts to hold the name tag to our mailbox and when I tried to brush off the snow, the name tag was wiped off with no resistance at all. The bolts had no strength at all in the cold weather. In the summer you could yank the name tag and it held. I very rarely fly in Winter, but I keep this in mind. I think this is one of the reasons pure Nylon only props are no longer made, at least in the bigger sizes. Fiberglass reinforced Nylon is used for props now and they are better all around. For the smaller sizes like 4-40 or even 2-56 there are Aluminum bolts available that are just as light as the Nylon ones and I use these for many things on models. The small Nylon bolts break too easy even when threading into Balsa sometimes.
Old 12-01-2005, 06:43 PM
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Default RE: STEEL BOLTS or PLASTIC

Marwen,

Could you have gotten your hands on some metric nylon bolts, by any chance? Lay the two bolts (nylon and metal) thread-against-thread. The threads should mesh perfectly if they're the same size.

That happened to me once...

Just a thought

Bob
Old 12-01-2005, 09:28 PM
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Default RE: STEEL BOLTS or PLASTIC

Oh, I suppose that's alway possible. But if you recall, I had stated gefore, "when I make it thread from the opposite end, it goues right in"

Now then, that being said, I never did finish the thought. Once it hits the opposite end, it jams up. This process of elimination told me that I had the right thread - there was was definately something woring with the overall situation. Also, again, keep in mind that there was not just on of them, but two. Thay BOTH performed in the same way!

At this point in time, not a really big issue though.

marwen
Old 12-01-2005, 09:36 PM
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Default RE: STEEL BOLTS or PLASTIC

Sorry, Marwen... I didn't read close enough. Apologies...

Bob
Old 12-01-2005, 11:49 PM
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marwen1
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Default RE: STEEL BOLTS or PLASTIC

Not a problem, Bob. You probably missed because I get to typing so darn fast that I forget where the keys are.

Who knows what I really said. LOL

My issues go just a litttle past that right now. This plane is about a 99% bashing of the plans. All I had to begin with was a two page (split in half) drawing that was top, front, and side view with a little bit of 1940's FREE FLIGHT text.

A lot of question on-line, a lot of posted images, a complete overhaul of thr rudder & stab, added ailerons & spoilers, and I even left room for flaps.

At this point, one of the wings is almost done and I'm thinking that I just might put the flaps in right now. Even if I don't use them right away, at least they are only a servo or two away from working. It is 96". The servo tray and two servos are in the fuselage right now. The aft end control rods are in place. I just finished weighing her.

With but ONE wing that weighs in at 4.25 oz (now) I doubled that weight, and then got a total weight of 2:19oz

Still have to add the servos for the spoilers and ailerons.
I can't make up my mind as to whether I want to MONOKOTE it or glass and paint it

Oh shucks, choices, choices.

Do you have any idea what a bird like this SHOULD weigh?

also, opinions on the monokote or glass.

I'll probably piddle with this thing till springtime. No rush!

This a hobby, I think. LOL

marwen

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